Method of producing extruded shapes



Jan. 12, 1965' G. F. KOTRBATY 3,164,398

METHOD OF PRODUCING EXTRUDED SHAPES Filed Aug. 9, 1960 2 Sheets-Sheet 1 INVENTOR GuYF KOTR BATY.

ATTORNEY Jan. 12, 1965 e. F. KOTRBATY METHOD OF PRODUCING EXTRUDED SHAPES 2 Sheets-Sheet 2 R my m we a 0m m K Fl ww Y U 6 m? Q mw N9 I hi E .v om mm mn m am Nm m f mm on a? g .3 mm E 2 mm 6 ATTORNEY United States Patent 6 3,164,898 METHOD OF PRODUCING EXTRUDED SHAPES Guy F. Kotrbaty, 56 Pondfield Road W., Brouxville, N .Y. Filed Aug. 9, 1960, Ser. No. 48,438 22 Claims. or. 29-553) This invention relates to animproved method of producing extruded shapes from metals and metal alloys, and more particulary to a novel method of producing finished extrusions of larger dimensions than the circumscribed diameter of the press die from which they are extruded.

In the currently employed method of producing extruded metallic shapes, such as aluminum, brass, copper, and magnesium base alloys, the maximum length, \vidthand depth'of the extrusion is limited essentially by amass Patented Jan. 12, 1965 of the shape.

three factors, namely, the eifective pressure behind the ingots or billets, the Weight and size of the ingot or billet and the circumscribed circle of the orifice of the die. In light of these limitations the preponderate number of extrusion presses in use are limited to a 12 in. container or less, while presses having an 8' in. or smaller die orificc account for approximately 95% of the extrusion presses in this country. The principal and compelling reason for this size limitation is the tremendous cost of extrusion presses that can extrude larger shapes. Extrusion presses having a container diameter of up to 24 in. have been built and operated by certain ofthe large aluminum producing companies. The cost of such installations ranges up to million dollars and their installation and'production costs are sohigh that they are feasible only for large runs or for important. defense items.

Major factors entering-intosuch costs are the great expense of the precision diesemployed and the relatively prolonged set-up anddoWn-time involve d in the procluctionschedules. Furthermore, 'a. limiting factor in the useof suchtlargerpresses is th'at'the larger'the circumscribed diameter die orifice of'lthe press the more it is limited in producing shapes having thin 'walli'sections.

Hence the wider the section or shape required, the thicker the-wall" section must be, .making-it unduly heavy and costly, and uneconomical for most uses. In view of these units, and hence they are-presently excluded from the field of large circumscribedffcircle diameter extruded Another objective of the invention is to devise an improved process for producing extruded metallic shapes in which theratio of the circumscribing diameter of the shape to the circumscribed diameter of the die orifice is at least 2 to 1. p

A still further objective of the invention is to devise an improved method of producing extruded metallic shapes by a novel integration of preliminary extrusion, and subsequent selective cross-section reduction of portions of the shape. 7

With these and other equally important objectives in View, the invention comprehends the concept of extruding an intermediate shape comprised of portions of the Inthe drawings: j l h FIGURE'I is aflow sheet illustrating the'several integr'al stages of operation in the production. of the novel en larged extruded shapes;

FIGS. 2' and S ars transverse vertical sectional views of extruded shapes, shown in relation to the' diameter circular die area, which shapes embody a single enlarged Web or reservoir of metal in therib portion of the shape; FIG. 4 is a view similar to FIGS. 2 and 3, in which the rib' portion 'of theextru ded shape embodies aplurality of ribs or potentially reducible metal blanks;

- FIG. '5 is a view similar to FIG. 3; in which t ewesportion ofthe extruded shape is of re-entrant or U con -,figuration having a'single rib; v

shapes, which field is now substantialy preempted by the operators of ultrahigh pressure extruders.

With the rapidly increasinguse of aluminum and its alloys in "the many fields of construction, there is an increased demand for shapes of greater Width and/ or depth with thin wall sections than thoseheretofore produced by the extant -r elatively low pressure extruders. While larger shapesmay be produced by fabrication from smaller extruded components, this not only involves additional cost incident to machining and joining thecomponents,

size limitationof an extruded metallic shape now imposed by current orthodox methods of production;

4 FIG. 6 is a viewsimilar to FIG. 5 in which a plurality of ribs is embodied in the 'Wehportion of the extruded shape;

. FIG; 7 is a view similar to FIG. 2,'sho wing sive and sequential or stage-wise reduction 'ofithe metal banks or ribs with accompanying lateral extension of the web. i

. As indicated hereinabove, the majority of metal ex truder installationshave acircular die diameter of 8 in. or

1 less. With such e'xtruders it ispossible to obtain anex- Anothersalient objective of the invention is to greatly a circumscribed circle diameter greater than that heretofore produced in such extruders. j

. Another object'ive of the invention is-to materially in crease the size ofgextruded metallicshapes utilizing currently installed extruders, bynovel integration of the; extruders 'with readily available accessmy equipment.-g

Yet another objective ofithe inventionis to produce truded panel of somewhat greater Widththan the circular diameter: of the die by first extruding a' V-shaped configuration, :and-then flatteningtheshape into a panel of maximum width. In this manner forexamplefa panel having a width of approximately 12 in. can be produced, usingan '8 in. extruder, and a panel having a Width: up toi40;in. may be produced from a 24 in. extruder. "It

will be noted, however, that the preformed shape is merely flattened without any reduction in thecross-section of any portion of the shape. ThenoveltyFand profound eco-,,

nomic significance of the invention-can be readily assessed when'it' is considered that invoking its principles, 'in

g i ribsjem bodied the vertical portions ,015 the web; and;

, ofindividual ribs in a particular extruded shape.

3 shapes of a width up to 100 in. or more, when employing an extruder having a 24 in. diameter circular die.

The novel method of producing extruded shapes of enlarged dimensions will readily be understood from a consideration of the flow sheet of FIG. 1 in which the major producing units are shown diagrammatically. As there illustrated, the method essentially comprises extruding a shape of novel configuration or design in the extruder stage A, and subsequently subjecting such initially formed shape to progressive reduction of selected areas thereof in a series of reduction stages B, between units of which stages the particular shape may be thermally treated during the progress of reduction, and finally subjected to a suitable heat treatment in a heating zone C to improve its mechanical properties.

Considered more in detail, the extruder may be of any standard size of the type currently in use, comprising, essentially, a hydraulic cylinder 1, a ram 2, a die holder 3 and a runout table 4 attached to the die holder. Within the die holder there is mounted any one of the selected dies adapted to produce a shape of the cross sectional contour shown in FIGS. 2 to 6, inclusive. In operation, the cylinder-actuated ram forces an inserted homogenized, preheated ingot or billet through the die and the emergent shape 5 is received on the runout table; upon completion of the ram stroke, the table and die holder are advanced hydraulically, and the butt end of the ingot is cropped. The extruded shape may be allowed to cool, and may then be straightened by stretching beyond its yield strength to remove distortion and to equalize strains. The shape is then processed in the reduction stage B, during which operation the thickness of theribs is progressively and sequentially reduced, and the metal embodied in a rib or ribs is displaced laterally of the longitudinal section of ample, by means of. presses, power brakes, or other techniqu'es,' such as hot or cold roller reduction or combinations thereof. As shown in FIGS. 1 and 8, themetal reduction is elfected in'a series of tandem rolling machines-- comprised of any selected number of units 6, 7, 8 and 9.

As. will be appreciatedythe numberof such units employed or required will depend essentially on the cross .sectional thickness of the rib or ribs, and on the number The roller reduction units maybe of any suitable type, such I as two-high units shown, having rolls 10 and 11,

mounted in the stand 12, and driven in the usual manner. As will be appreciated, the width and size of the rollers in the several units may vary, depending on the number of reduction passes required for any particular extruded shape, the width being selected to accommodate the increased width of the progressively laterally expanding extruded shape.

Interposed between certain of the roller stands, or between selected groups of tandem rolls, is one or more induction heating stages 13,14 and 15, which may function as intermediate stress annealing stages during cold roll reduction, or as preheating st-ages during hot roll reduc tion, the temperatures of the stages being suitably controlled for these respective purposes, in accordance with current practice.

. After final reduction of the ribs to the desired ultimate cross section, the shape may be heat treated in a horimay bestraightened in a suitablestretcher; not shown,

to remove distortion and to relieve internalstresses. In

the case of wrought, non-heat treatable alloys, the temper may be strain hardened, strain hardened and partially annealed, or strain hardened and stabilized. With some of the shapes the final straightening may be effected on a roller straightener, not shown. The finished expanded shape thus produced may, if desired, be further treated by anodizing or the like, to improve its surface characteristics. Where greater accuracy and close tolerences are required, the shape may be pulled through a final sizing die. Similarly, if desired, the finished expanded extruded shape may be treated as by rolling or pressing to modify the contour or profile of any of the web or flange portions thereof.

In accordance with the present invention, the design and profile of the as-extruded shape is chosen to most effectively utilize the circular die area of the particular extruder, while insuring the incorporation of suificient metal in the ribs or banks to provide for the subsequent lateral or vertical extension of selected sections of the shape during the roller reduction process. Any selected number of ribs may be embodied in the extruded shape, and the ribs may be of any desired configuration to most elfectively correlate them with the particular reduction technique employed, and with the desired size and shape of the final product. Thus, the total mass of metal embodied in the rib portion which is to be reduced to the same cross section as the integral, initially formed web portion may be incorporated in a single rib or mass or may be divided or distributed between a plurality of smaller ribs or masses. The number of reduction passes or the number of pairs of rolls used in the reduction stage and, in the case of cold roll reduction, the number of intermediate anneals, will depend to a very considerable degree on the thickness of the ribs which are to be reduced; thus a thicker rib will require more reduction passes than one of thinner section. The number ofpasses will also depend, to some degree, on the configuration of the as-formed ribs, i.e., whether these are substantially circular, semicircular, convex or the like, and also on the related configuration of the sections of the reducing rolls which contact the protuberant ribs. For a given shape the total mass of the to-be-reduced metal which is to be embodied therein, to secure any predetermined extension in one or more dimensions of theultimate finished product, can readily be calculated and its distribution in the shape can be chosen to most effectively and economically insure it reduction.

merely characteristic shapes and not the completeor ex-. elusive range which may be utilized.

Referring to FIG. 2, there is shown a simple design of a shape producible according to the invention for the prov duction, for example, of a panel structural member. This shape comprises a web member having a horizontal plate or web portion 17 and integral vertical legs 18 formed with terminal inturned flanges 119. Incorporated in the central portion of the plate or web 17, the total mass of metal which is to be subjected to reduction is in the form of a relatively elongated cylindrical section 20. The mass of metal in this rib or metal bank is that which has been previously calculated to give the desired lateral extensioniof the-panel when such rib is progressively reduced by roller or power. press reduction to the same cross'section'as the contiguous plate section 17. This shape represents the simplest form or design calculated to produce a desired extension with the minimum number of reduction passes and with minimum annealing.

'In FIG. 3, there is shown a shape generally similar to that'shown in FIG. 2, having the plate or web section 21, integral legs 22 with inturned flanges 23 anda metal bank orrib portion :24 inthe form of a mass of circular cross section embodied in the central longitudinal'portion of'the web 21, the mass of'which is sufficient to produce a lateral extension of the panel equivalent tothat formed from the shape shown in FIG. 2.

In FIG. 4 there is illustrated," in simple form, the subdivision of the total necessary metal bank into a plurality of reducible ribs. The shape comprises a web or plate section 2.5, integral vertical legs 26 formed with the inturned dlanges 27 and a metal bank comprising separate spaced ribs 28, 29 and 30 integrally embodied in the tobe-extended upper web or plate 25. Generally considered a shape of such design requires fewer reduction passes and fewer anneals than a shape of the type shown in FIG. 3. Such designed shape also simplifies the reduction process because the smaller ribs 28, 29, and 30 require less mechanical force to reduce them .to the required web thickness and therefore can be reduced utilizing smaller, lighter and less expensive machinery, without limiting the ultimate size. of the final finished product. This type of shape also insures more accurate control of the extension of the lateral dimension of the web to its desired ultimate width. I

In FIG. 5 there is illustrated another form or design of an as-extruded shape in which the circular die area is utilized to initially form a greater portion of the ultimate width of the end product than the designs previously described. In such design the as-extruded shape comprises a relatively extensive webincorporating upper plate sections 31 having reentrant vertical extensions 32, of the same 'cross'section asthe contiguous sections .31, and in- In FIG. 6 there is shown an ext-rudedflshapedesign.

similar to-that of HG. 5, in which the calculated total mass of metal required tor-the desired extension of a web is distributed equally between a plurality of appropriately'positioned' ribs. The shape may comprise upper web portions 36 having integral reentrantextensions 7 ,and integral legs 33, each of which is' formed-with an inturnedtlange 39. The-las-extruded shape embodies rib in. and a leg'depth of 3.5 inches.

sections'ttiandtl inthe upper-web portions 36, and a H case of the shape shown in FIG. 5,,p'rior to reducing the T rib sections in the reduction rolls, the as-extruded shape is flattened -by rolling "or. pressing to its maximum 'widt-h to permit subsequent extenuation by reduction working of the metal maybe invokedtfo widen preformed shapes of the type shown in FIGS. 2m 6, or to deepen portlons of the shape in *FIG. 7. Referring to FIG. 7, the as-extruded shape comprisesan upperilat web portion 43 of the legs, will extenuate the legsto the desired, preselected dimension. Aslwill be understood, inthe reduction stage the extruded shape is ted tothe reduction. rolls with the 7 'legs 44 in a horizontal position, parallelto the axes of the rolls. In thistype .of reduction the shape may be ted to .a spaced, in-line series of roller stands comprisedofa ribs 46 inea clrleg maybe reduced simultaneously and to 3 More simply, if desired, the tobe-rerib section .42 in the rcentrant extension 37. Asin the duced shape may be fed to a series of typical longitudinally spaced tandem or two-high rolls to reduce the rib in one leg to a selected cross section, after which the shape may be inverted and repassed through such group of rolls to reduce the rib in the opposite leg to the same degree. The thus partially reduced shape may be then annealed, in the case of cold reduction, and the sequential, stage-wise reduction of the rib or ribs repeated to the extent necessary to secure the desired ultimate reduction. While the legs 44 are shown as having inturned terminal flanges 45, these may be omitted in the as-extruded shape, and subsequently formed, by appropriate pressing or shaping operations, after the ribs havebeen completely reduced. As in the previous cases of extenuation of ribs in the upper web portion of a shape, the ribs embodied in the to-be-extruded leg portions of an extruded shape may be of any desired contour or profile best calculated and designed to achieve most efiicient reduction by the particular design of the reduction r olls.

employed; thus the ribs may, as shown, be of circular cross section, however, for correlation with specially designed roller members the ribs may be of other profile or cross section, such as semicircular, ellipsoidal, semiellipsoidal, or the like.

The sequential phases. of the direct line production of the novel expanded extruded shape will be seen from a.

consideration of FIGS. '1 and 8. In FIG. 8 there is shown a shape, extruded from a press having a circumscribed circle of 5 in. diameter, from which is ultimately produced a shape of panel configuration having a web width of 16 7 It is to be particularly noted that the orthodox method of producinga shape of this width would require a'press having a circumscribed 0.0625 in., and the area ofeach of the integral ribs is 0.1936 inches." "Whenthese several ribs are Zreduced to the same cross section as that of web 47 the area of the panel in the upper web is increased by 0.78125 'sq..in. per

foot of the panel section.

As will be seen inFIG'. f1, as the shape is extruded .it i .is received on the. runout'table 4and the butt'end is sheared orfcropped, and while still hot itj'lS fed to the" 50 v direct line of the metal reduction units and passed sequentially. through the units." In such direct or immediate passage of 'theextruded'shape to the roller millsfits temperatur'e (extrusion temperature) i's'oftheorder of 380 selected width and orosssection, and integral angularly disposed legs 'M-terminating in intu'rned flanges 4:5. -Em-- bodied-in the legs 44 arernetal ribs 46 of a preselected 7 mass which, when reduced'to the samecross section. as

i 'taneously'reduced in a'second' stage," and then the ribs 51:

1 pair of tandemortwo-high rolls vertically spaceda distance equal to the widthpf the web. portion 43, and the the samedegi'ee' or extentineach pass through the re- 'diiction to,420 .C., and hence it is thermally prepared forhot rolling operations; however, if desired, the shape may be flu the process of reducingthe metal ribs, and commensurately extending their mass intoa continuous web of selected thickness, the ribs are reduced in stages; thusfas Y is illustrated in FIG. 8, in extending the upper web the central'rib 53 is first reduced to a selected cross section in one stage, and thereafter the ribsSZ and 54 are simul'- and l55 are reduced in'the final stage so that the webi is progressively laterally'extended from thecenter or theweb section outwardly towards-the sides of thepa nel. In'the preferred operation, the metal reduction of the ribs may be effected in three phases, namely, a primary breakdown 'or hot rolling operation in'which, in ,ajseriesfof passes' I a rib is reducedby from approximately .60 to percent .75'

of-the desired ultimate reduction, while-.maintaining its ti Crystalline structure; an intermediate roughing cold rolling, to etfect a reduction in thickness, close to the ultimate desired reduction, and a finishing or planitizing rolling operation, between smooth highly finished rolls, with but slight reduction to give a hard surface and to establish accurate, uniform thickness of the web within narrow limits. In the preliminary roughing or hot rolling phase of the rib reduction, it is advantageous to use small diameter rolls because of their deeper bite or nip into the metal, and larger diameter rolls for the intermediate and finishing reductions. When small diameter rolls are used it is desirable to employ three-high or four-high stands to insure the rigidity of the rolls.

The stage-wise reduction of the ribs and the consequent progressive lateral extension of the upper Web is depicted in FIG. 8. As there shown, the rib 53 which may he at a temperature of 380 C. to 420 C. or more, is worked in a selected number of passes until it is reduced in cross section passing from its original circular form to assume a generally flattened and widened section shown at 56 to 53. Such reduction may be effected by employing a series of in-line roller stands or, if desired, in a reversing mill. At such stage of reduction the temperature of the shape is lowered-to a point where further reduction (cold rolling) results in some work hardening, and at this stage the shape may be reheated, utilizing an induction or the furnace heater13, and additional hot rolling continued, or the partially reduced rib 56 may be further reduced in a selected number of cold roll passes until it assumes a wider and thinner form as shown at 58. At this point, if the reduced metal section is work hardened .to an undesired extent'the piece may be rapidly annealed in one of the furnaces shown in FIG. 1 and then subjected to further reduction in an in-line series of roller mills, or in a single reversing mill, until the reduced segment or section 58 is of the same cross section as, and co-extensive with, the web portion between the unreduced ribs 52 and 54. V

In the next stage of reduction, as previously explained, the ribs at the termini of the reduced section 53 are simultaneously and progressively reduced in a series of similar stage-wise reductions, such ribs being progressively reduced or flattened to form sections59, 6t and 61.

In the third stage a similarseries of roller reductions is carried out to reduce the ribs 51 and 55 to the progressively reduced sections 62, 63, and 64. The shape may thenbe straightened, if required, by stretching or by roller straightening to produce thefinal shape in which the legs 48 are identical'inshape and dimensions as in the as-extruded shape, whereasthe originalweb portion embodying the several ribs comprises a continuous widened webof uniform cross section. When the shape produced is comprisedof a heat treatable wrought alloy it may be of any selected temper, either as fabricated or annealed, or it may be given any desired higher temper,

such as T T T T or T,; by suitable treatment in a mills employed in the different stages of rib reduction are correlated in' size'and design with the profile of the shape processed therein, so that the rollers selectively contact only the rib or ribs unrlerg'oin reduction in the different stages; thus the rollers mounted in the stands used in the reduction of rib 53 are so designed as to contact and reduce such rib without any reductive action on adjacent ribs 52 and 54; similarly, the rollersmounted in the stands used in the reduction ofrihs 52 and 54 are designe'dto designed for its particular operation, for example, the

rollers may be of a generally cylindrical form having a section or sections of-modified diameter or camber 'so positioned along the axis of the rolls as to contact only the rib or ribs which are to be reduced. As is known in the usual type of rolling operations, the rolled metal has a plane of symmetry and the reduction of the metal tends to elongate it in a plane of symmetry normal to the axes of the rolls with but little spread being produced in its width; in such typical rolling operations the piece or slab subjected to rolling contact can elongate because there are no restrictive forces opposing such elongation. In the rolling operations described herein the normal tendency or" the ribs of the web to elongate is opposed or restricted by their integral lateral web extensions which are not being worked or reduced, and hence the tendency of the rib to elongate is opposed by the adjoining tensioncd, diametrically positioned Web sections. The lateral component of movement of the metal undergoing reduction is less restricted, such restriction being imposed only by the inherent stiitness of the relatively thin web section whose side edges are unconfined, thus allowing the web to be displaced laterally. It will be appreciated that the lateral component of the force tending to widen the upper web portion can be increased by proper design of the camber of the rib-contacting portions of the rolls.

The extended extruded shapes, produced according to the present invention, may be given a surface finish best adapted to improve their appearance, usefulness and endurance for any general or special intended use; thus the shapes may be given any of the mechanical, chemical or electrochemical finishes to which aluminum alloys are amenable. The individual unit shapes produced asdescribed herein may be joined by any applicable welding technique to produce a great variety of larger integral forms and shapes for use in various fields of construction.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the precise details set forth by Way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit of theinvention or exceeding the scope of'the appended claims.

I claim: v I

1. A process of producing an extruded metallic shape of a width substantially greater than the diameter of the circumscribed circle of the die orifice of an extrusion -press, comprising extruding a shape having a web portion of uniform cross-section and an integral mass of substantially greater cross-section than the cross-section of the web portion, saidmass providing a material bank of formable metal, subsequently passing the extruded shape through a series of reduction zones and progressively reducing the cross-section of the material bank to progressively'extend the Width of the shape while maintaining the truded shape is comprised of a non ferrous alloy.

5. A process according to claim 1, in which the extruded shape is comprised of a ferrous alloy.

6. A process in accordance with claim 4, in which the non-ferrous alloy is chosen from the group consisting of aluminum and magnesium base alloys. I

7. A process of producing an extruded shape of a metallic alloy of a Width substantially greater than the diameter of the circumscribed circle of the die orifice of an extrusion press, comprising extruding a shape having a Web portion of uniform cross-section and of parallel integral, longitudinal ribs of substantially greater cross section than the cross-section of the webportion, subsequently passing the extruded shape through a series of reduction Zones and progressively reducing the crosssection of the ribs while progressively extending the width of the shapeuntil the cross-section of the rib is equal to that of the web portion.

8. A process according to claim 7, in which hot reduction is effected in said reduction zones.

9. A process according to claim 7, in which hot rolled reduction is ettectedin said reduction zones.

10. A process according to claim 7, in which cold reduction is effected in said reduction zones. i

11. A process according to claim 7, in which cold rolled reduction is elfected in said reduction zones.

12. A process according to claim 7, in whichthe mass of metal embodied in the integral longitudinal rib exceeds that embodied in the web portion.

13. A process of producing extruded, wide web shapes of metallic alloys which comprises extruding a shape having web portions of uniform cross-section of the desired ultimate thickness and integral portions of substantially greater thickness than the said web portions extending lengthwise of the extruded shape; continuously passing the extruded shape through a series of reduction zones and therein selectively and progressively reducing the cross-sections of said integral portions while progressively extending the width of the shape until the cross-sections of the integral portions equal that of the web portions.

14. A process, according to claim 13, in which hot reduction is effected in said reduction zones.

15. A process, according to claim 13, in which cold reduction is eflected in said reduction zones.

16. A process, according to claim 13, in which hot reduction is effected in certain of said reduction zones and cold reduction is effected in the other reduction zones.

17. A process, according to claim 13, in which the said shape is annealed between selected zones of the series.

18. A process, in accordance with claim 13, in which the shape is subjected to inductive heating prior to passage through certain of the series of reduction zones.

19. A process, accordingto claim 13, in which the mass of metal embodied in the said integral portions exceeds that embodied in the web portions.

20. A process, according to claim 13, in which the width of the shape after final reduction is at least twice that of the initially extruded shape.

21. A process, according to claim 13, in which the metallic alloy is a nornferrous alloy.

22. A process for producing extruded shapes of a non ferrous alloy of a Width considerably greater than the limiting width of light press extruders having a circumscribed circle die orifice of the order of 5 to 8 inches, which comprises initially extruding a shape from such alloy, said extrusion embodying Web portions of selected ultimate thickness and a thicker intermediate portion extending the full length of the shape, said intermediate portion embodying a mass of metal considerably greater than that of the web portions; progressively passing the extruded shape through a series of reduction zones and progressively reducing the cross-section of the said thicker intermediate portion while progressively extending the width of the shape until the cross-section of the intermediate portion equals that of the initially formed Webs.

References Cited in the file of this patent 

1. A PROCESS OF PRODUCING AN EXTRUDED METALLIC SHAPE OF A WIDTH SUBSTANTIALLY GREATER THAN THE DIAMETER OF THE CIRCUMSCRIBED CIRCLE OF THE DIE ORIFICE OF AN EXTRUSION PRESS, COMPRISING EXTRUDING A SHAPE HAVING A WEB PORTION OF UNIFORM CROSS-SECTION AND AN INTEGRAL MASS OF SUBSTANTIALLY GREATER CROSS-SECTION THAN THE CROSS-SECTION OF THE WEB PORTION, SAID MASS PROVIDING A MATERIAL BANK OF FORMABLE MTAL, SUBSEQUENTLY PASSING THE EXTRUDED SHAPE THROUGH A SERIES OF REDUCTION ZONES AND PROGRESSIVELY REDUCING THE CROSS-SECTION OF THE MATERIAL BANK TO PROGRESSIVELY EXTEND THE WIDTH OF HTE SHAPE WHILE MAINTAINING TH CROSS-SECTION OF THE WEB PORTION UNTIL THE CROSS-SECTION OF THE MATERIAL BANK IS EQUAL TO THAT OF THE WEB PORTION 